Disallow freeze format with pip list --outdated (#11482)

Co-authored-by: Tzu-ping Chung <[email protected]>

Author: Mr-Pepe

news/9789.removal.rst

@@ -0,0 +1 @@
+Remove the ability to use ``pip list --outdated`` in combination with ``--format=freeze``.

src/pip/_internal/commands/list.py

@@ -155,6 +155,11 @@ def run(self, options: Values, args: List[str]) -> int:
         if options.outdated and options.uptodate:
             raise CommandError("Options --outdated and --uptodate cannot be combined.")
 
+        if options.outdated and options.list_format == "freeze":
+            raise CommandError(
+                "List format 'freeze' can not be used with the --outdated option."
+            )
+
         cmdoptions.check_list_path_option(options)
 
         skip = set(stdlib_pkgs)

tests/functional/test_list.py

@@ -577,16 +577,20 @@ def test_outdated_formats(script: PipTestEnvironment, data: TestData) -> None:
     assert "Package Version Latest Type" in result.stdout
     assert "simple  1.0     1.1    wheel" in result.stdout
 
-    # Check freeze
+    # Check that freeze is not allowed
     result = script.pip(
         "list",
         "--no-index",
         "--find-links",
         wheelhouse_path,
         "--outdated",
         "--format=freeze",
+        expect_error=True,
+    )
+    assert (
+        "List format 'freeze' can not be used with the --outdated option."
+        in result.stderr
     )
-    assert "simple==1.0" in result.stdout
 
     # Check json
     result = script.pip(